Needs mobi2mobi, then pick an ebook, enter an ASIN and hit convert to get back a mobi file set up for sideloaded Whispersync.

I'm not sure if anyone feels a need for it? I'm after any useful feedback/faults then I'll clean up the source a bit, finish off and formally release (fully honouring the GPL that the mobi2mobi GUI is under, I'm just not happy with some of my code right now, needs cleaning up before releasing, consider this a teaser...)